High refractive index and optically clear copoly (carbosilane and siloxane) elastomers

ABSTRACT

High refractive index and optically clear copoly(carbosilane and siloxane) elastomers and ophthalmic lenses made therefrom are provided. The elastomers are comprised of copolymers having carbosilane repeat units and siloxane repeat units. The copolymers and ophthalmic lenses of the present invention have a high refractive index and excellent folding recoverability.

FIELD OF THE INVENTION

[0001] The present invention is directed to high refractive index andoptically clear elastomers, and ophthalmic lenses formed therefrom. Moreparticularly, the invention relates to copoly(carbosilane and siloxane)elastomers.

BACKGROUND OF THE INVENTION

[0002] The physiology of the human eye includes an anterior chamberlocated between the cornea, or outer surface of the clear part of theeye, and the iris, the pigmented portion of the eye that is responsiveto light, and a posterior chamber, filled with vitreous humor. Acrystalline lens, which includes a lens matrix contained within acapsular bag, is located behind the iris and separates the iris from theposterior chamber. The crystalline lens is attached to the ciliarymuscle by cord-like structures called zonules. Lining the rear of theposterior chamber is the retina, the light sensing organ of the eye,that is an extension of the optic nerve. In young, healthy eyes,contraction and relaxation of the ciliary muscle shapes the naturalcrystalline lens to the appropriate optical configuration for focusinglight rays entering the eye on the retina.

[0003] As the natural crystalline lens ages, however, the structure ofthe lens matrix of the crystalline lens changes, becoming hazy andrelatively inflexible. Eventually, the hazing of the lens matrix mayprogress to the point where the lens is considered cataractous, whichmay seriously occlude the amount of light passing through thecrystalline lens and ultimately onto the retina. Fortunately, modernsurgical techniques have been developed which allow removal of thecataractous lens matrix so that light may once again pass unimpeded ontothe retina.

[0004] Presently, a cataractous crystalline lens matrix is removed froman eye using a procedure whereby the cataractous natural lens matrix isextracted from the capsular bag of the lens through an anteriorcapsulotomy. Typically, the cataractous lens matrix is removed from thecapsular bag through the anterior capsulotomy using phaco-emulsificationand aspiration. Alternatively, the cataractous lens matrix may beremoved using several other well known techniques whereby thecataractous material is broken up and aspirated from the capsular bag.After extraction of the cataractous lens matrix, an intraocular lens maybe implanted within the remaining capsular bag. However, while theprocedure to remove the emulsified natural lens can be accomplished withabout a three millimeter incision in the cornea, about at least a sixmillimeter incision is required to accommodate the full diameter of theintraocular lens to be implanted.

[0005] In order to reduce the size of the incision required forimplantation of an intraocular lens, and thus limit the trauma to theeye, intraocular lenses made of relatively soft material that can berolled, folded or otherwise deformed for insertion into the eye weredeveloped, replacing conventional intraocular lenses made of relativelyhard material, such as polymethylmethacrylate (PMMA). Soft intraocularlens must exhibit a number of important mechanical and physicalproperties to be suitable as an implant. For instance, soft intraocularlenses should have low glass transition temperatures so that they can bereadily folded for implantation at room temperature. In addition, thethickness of the intraocular lens should be minimized in order to reducethe overall size of the folded or rolled lens. Thus, soft intraocularlenses should have a high refractive index so that the lenses will havethe requisite refractory power at a minimal thickness. The lenses shouldalso exhibit a high degree of softness to improve the foldability of thelenses, thereby reducing the size of the folded lens, while stillretaining other mechanical properties, such as tensile strength andfolding recoverability. Further, the lenses must be optically clear.

[0006] Prior art soft intraocular lenses made of silicone materialstypically have very low glass transition temperatures (lower than −100°C.), permitting them to be readily folded or rolled at room temperature.However, other properties of silicone lenses could be improved in orderto minimize the size of the folded lens. It would be desirable toprovide a silicone material for use as an intraocular lens that has ahigh refractive index and softness to reduce the size of the foldedlens. It would also be desirable to provide a silicone material that hasother properties suitable for use as an intraocular lens such as highfolding recoverability and optical clarity.

[0007] What has been needed and heretofore unavailable, is a siliconematerial having improved properties, including a high refractive index,softness, optical clarity and excellent folding recoverability, for usein intraocular lenses. The present invention satisfies these needs andothers.

SUMMARY OF THE INVENTION

[0008] The present invention provides copoly(carbosilane and siloxane)elastomers useful in the fabrication of ophthalmic lenses, includingintraocular lenses and other implantable ocular devices, such asintraocular contact lenses.

[0009] In one embodiment, the copoly(carbosilane and siloxane) elastomercomprises a copolymer having carbosilane repeat units and siloxanerepeat units. Each carbosilane repeat unit has a carbon chain with 2 to12 carbon atoms. Each siloxane repeat unit may be individually selectedfrom the group comprising dimethylsiloxane and diphenylsiloxane.

[0010] The copolymers of the present invention also have terminalalkynyl groups in one embodiment. More particularly, each terminalalkynyl group may be selected from the group consisting of vinyl, allyl,vinylphenyl, allylphenyl, vinylbenzyl and allylbenzyl.

[0011] In another embodiment, the copolymer has the structure (I):

[0012] wherein A is an alkynyl; R₁, R₂, R₃, and R₄ are each ahydrocarbon group; Ph is a phenyl; n is an integer from 10 to 500; m isan integer from 5 to 100; o is an integer from 2 to 12; and p is aninteger from 2 to 50.

[0013] In other embodiments, additional materials are also included inthe elastomer to achieve desired properties. In one embodiment, theelastomer includes a platinum catalyst. In another embodiment, theelastomer includes a crosslinking agent, such as an organohydrosilanehaving multiple hydride groups or containing multiple hydride grouppolymers. More particularly, the crosslinking agent is ahydrodimethyl-terminated silazane in one embodiment. In yet anotherembodiment, a filler that is hexamethyldisilazane-treated silica andsilicone resin material is added to the elastomer. Further, anultraviolet (UV) light absorbing compound, such as allyl or methallylfunctionalized benzotriazoles and benzophenones, may also be included inthe elastomer.

[0014] The elastomers of the present invention have a high refractiveindex, at least about 1.43 in one embodiment. The elastomers also haveexcellent folding recoverability.

[0015] In one embodiment, an ophthalmic lens is formed from thecopoly(carbosilane and siloxane) elastomers. In particular, theophthalmic lens may be an intraocular lens. The ophthalmic lens may alsobe an intraocular contact lens or other implantable ocular device.

[0016] The elastomers of the present invention are particularly suitedfor use in ophthalmic lenses due to their high refractive index andoptical clarity. The elastomers are also soft materials with excellentfolding recoverability, permitting lenses formed therefrom to be foldedor rolled to a minimal size for insertion. The elastomers also have highstrength and flexibility and are photostable.

[0017] Other features and advantages of the invention will becomeapparent from the following detailed description, taken in conjunctionwith the drawings, which illustrate, by way of example, variousembodiments, principles and features of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]FIG. 1A is a top view of an embodiment of an intraocular lens ofthe present invention, having an optic and a pair of haptics;

[0019]FIG. 1B is a side view of the embodiment of FIG. 1A;

[0020]FIG. 2A is a top view of an embodiment of an intraocular lens ofthe present invention having an optic and a pair of plate-type haptics;and

[0021]FIG. 2B is a side view of the embodiment of FIG. 2A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The present invention relates to elastomers having a highrefractive index and optical clarity, and ophthalmic lenses madetherefrom. Specifically, the invention relates to copoly(carbosilane andsiloxane) elastomers having a high refractive index and optical claritythat are suitable for implantation within an eye of a patient.

[0023] The elastomers of the present invention include a copolymerhaving carbosilane repeat units and siloxane repeat units. In oneembodiment, each carbosilane repeat unit has a carbon chain with 2 to 12carbon atoms. Generally, about 2 to 50 carbosilane repeat units arepresent in a chain of the copolymer, although more carbosilane repeatunits, such as 50 or more, may be present. The carbosilane repeat unitsgenerally comprise about 2% to 5% by weight of the copolymer.

[0024] The copolymers of the present invention also include siloxanerepeat units. The siloxane repeat units have up to two carbon groupsattached to each silicon atom in one embodiment. These carbon groups maybe methyl or phenyl groups. In particular, suitable siloxane repeatunits include, but are not limited to, dimethylsiloxane,methylphenylsiloxane, and diphenylsiloxane. Generally, about 10 to 500dimethylsiloxane repeat units and about 5 to 500 diphenylsiloxane repeatunits are present in a chain of the copolymer. The dimethylsiloxane anddiphenylsiloxane repeat units generally comprise about 50% to 98% byweight of the copolymer.

[0025] In one embodiment, the copoly(carbosilane and siloxane) is arandom copolymer having the structure (I):

[0026] wherein A is an alkynyl; R₁, R₂, R₃, and R₄ are each ahydrocarbon group; Ph is a phenyl; n is an integer from 10 to 500; m isan integer from 5 to 100; o is an integer from 2 to 12; and p is aninteger from 2 to 50.

[0027] Suitable terminal alkynyl groups (A) include, but are not limitedto, vinyl, allyl, vinylphenyl, allylphenyl, vinylbenzyl and allylbenzyl.The suitable hydrocarbon groups for R₁, R₂, R₃, and R₄ include but arenot limited to allyl or aryl groups, such as ethyl, methyl, propyl,butyl and phenyl.

[0028] The elastomer may include a platinum catalyst, such as a platinumdivinyl complex having 2-3% platinum in xylene, that is added tocatalyze the curing of the elastomer, as is well known in the art.Additionally, the elastomer may include a crosslinking agent. Suitablecrosslinking agents include organohydrosilanes having multiple hydridegroups or containing multiple hydride group polymers. In one embodiment,a hydrodimethyl-terminated silicone is used as the crosslinking agent.

[0029] A filler may also be included in the elastomer to reinforce themechanical properties of the crosslinked elastomer. In one embodiment,the filler is hexamethyldisilazane-treated silica and silicone resinmaterial. The filler may be added in amount of about 8-25 parts fillerto 75-92 parts copolymer.

[0030] The elastomers of the present invention may also include anultraviolet (UV) light absorbing compound, such as allyl or methallylfunctionalized benzotriazoles or benzophenones, for protection againstexcessive UV radiation. The UV absorbing component maybe pre-linked tothe crosslinking agent or mixed in separately with thecopoly(carbosilane and siloxane).

[0031] The copolymer having carbosilane and siloxane repeat units may beprepared, for example, by the reaction of octamethylcyclotetrasiloxaneand octaphenylcyclotetrasiloxane with vinyl-terminated oligo(carbosilaneand siloxane) in the presence of an N-catalyst, such astetramethylammonium hydroxide or tetraethylammonium hydroxide, at hightemperature. The vinyl-terminated oligo(carbosilane and siloxane) mayhave a molecular weight of about 400 to 4000 and from 2 to 50 repeatunits of carbosilane. The viscosity of the base copolymer used in thepreparation of the final elastomer can range from about 500 cps to50,000 cps, and preferrably 2000 cps to 10000 cps. The base copolymermay then be cured to form the elastomer of the present invention bymethods well known in the art.

[0032] The resulting elastomers are soft, biocompatible and opticallyclear. The elastomers have a durometer Shore A hardness of at least 15.Further, they have an elongation of at least 100 percent, and a tensilestrength of at least about 100 psi, and preferably about 180 to 260 psi.The elastomers of the present invention have a high refractive index,between about 1.43 to 1.55 (at 20° C.) in one embodiment, and moreparticularly at least about 1.46 in another embodiment.

[0033] The elastomers are particularly useful in the fabrication ofophthalmic lenses and other implantable ocular devices, includingintraocular lenses and intraocular contact lenses. The elastomers may beadvantageously used for the lens body of the ophthalmic lens, or moreparticularly the optic of an intraocular lens. The elastomers are soft,biocompatible, and optically clear and have a high refractive index andhigh strength. They are capable of being deformed for insertion througha small incision in the cornea without breakage and have excellentfolding recoverability. The elastomers are also photostable.

[0034] The ophthalmic lens bodies may be molded at temperatures of 120°C. to 200° C.; preferably the molding temperature is in the range of145° C. to 160° C. In yet another embodiment, the lens mold may beshaped so as to produce a lens having suitable curves and geometry suchthat the molded lens requires little or no additional forming to providea finished lens.

[0035]FIG. 1A depicts an embodiment of an intraocular lens 10 of thepresent invention. The intraocular lens 10 has an optic 12 formed from aelastomer of the present invention and flexible haptics 14 forpositioning the intraocular lens 10 in the eye. The intraocular lens 10may have one or more haptics, although in this embodiment, two haptics14 are shown. Also, in this embodiment, the intraocular lens 10 is shownas a multi-piece lens wherein the optic 12 and the haptics 14 are formedfrom different materials and the haptics 14 are attached to the optic 12by conventional methods. The haptics 14 may be, for example, a filamentof PMMA, polyimide, Kynar™ or polypropylene formed by extrusion. As oneskilled in the art will appreciate, the intraocular lens mayalternatively be a one-piece design wherein the optic and haptics areformed from a single piece of the elastomer of the present invention.FIG. 1B depicts a side view of the intraocular lens 10 of FIG. 1A,further showing the optic 12 and haptics 14.

[0036]FIG. 2A depicts another embodiment of an intraocular lens of thepresent invention. In FIG. 2A, a plate-type haptics lens 16 having alens body 18 is shown. As seen from the illustration in FIG. 3A, thelens body 18 has a generally rectangular shape and includes a centraloptic zone or optic 20 formed from a elastomer of the present inventionand plate-type haptics 22 extending from diametrically opposite edges ofthe optic 20. FIG. 2B depicts a side-view of the plate-type haptics lens16 shown in FIG. 2A.

[0037] In addition, the elastomers of the present invention can be usedto produce other transparent objects requiring a high refractive indexand an optically clear, soft material.

[0038] The invention will now be further illustrated by the followingexamples which are intended to be illustrative and non-limiting.

EXAMPLE 1

[0039] This example illustrates the preparation of oligo(carbosilane andsiloxane) (A) which is used in the preparation of the copoly(carbosilaneand siloxane) elastomer. In a 250 ml three-necked round bottom flask,150 grams of 1,3-divinyltetramethyldisiloxane and 13 milligrams ofplatinum catalyst were stirred and heated to 100° C. Over a period of 25minutes, 25 grams of tetramethyldisiloxane were added dropwise to theflask. The mixture was stirred at 100° C for an additional hour. Excess1,3-divinyltetramethyldisiloxane was removed under vacuum conditionsuntil no further low boiling point material remained, leaving behind ayellow, slightly viscous material. GPC analysis showed that thismaterial had an average molecular weight of about 500. ¹H NMR spectrashowed that the material was oligo(carbosilane and siloxane).

EXAMPLE 2

[0040] A higher molecular weight oligo(carbosilane and siloxane) (B) wasprepared from the oligo(carbosilane and siloxane) (A) of Example 1 asfollows. In a 250 ml three-necked round bottom flask, 15 grams oftetramethyldisiloxane and 13 milligrams of platinum catalyst werestirred and heated to 80° C. Over a period of 15 minutes, 15 grams ofoligo(carbosilane and siloxane) (A) were added dropwise to the flask.The mixture was stirred at 100° C. for an additional hour. Excesstetramethyldisiloxane was removed under vacuum conditions until nofurther low boiling point material remained. The mixture was then cooledto room temperature.

[0041] Next, 50 grams of 1,3-divinyltetramethyldisiloxane and 13milligrams of catalyst are added to a second 250 ml three-necked roundbottom flask and stirred and heated to 100° C. Over a period of 15minutes, the material from the first flask was added dropwise to thesecond flask. The mixture was stirred at 100° C. for an additional hour.Low boiling point material was removed under high vacuum, leaving behinda yellow, high viscosity oligomer (B). GPC analysis showed that thismaterial had an average molecular weight of about 1000. ¹H NMR spectrashowed that the material was oligo(carbosilane and siloxane).

EXAMPLE 3

[0042] Examples 3 through 7 illustrate the preparation ofcopoly(carbosilane and siloxane) from oligo(carbosilane and siloxane) Aand B in accordance with principles of the present invention.

[0043] In a 500 ml three-necked round bottom flask, 44.6 grams ofoctaphenylcyclotetrasiloxane, 93.5 grams ofoctamethylcyclotetrasiloxane, 5.1 grams ofvinyldimethylsiloxy-terminated oligo(carbosilane and siloxane) (B) and0.14 grams of N-catalyst were mixed. The mixture was stirred and heatedto 100° to 120° C. for 2 to 4 hours until theoctaphenylcyclotetrasiloxane had completely dissolved and the mixtureturned into a viscous brown solution. The mixture was then cooled toroom temperature and 150 ml of methylene chloride was added and stirredinto the mixture. Next, 75 ml of methyl alcohol and 100 ml of distilledwater were added and the mixture was stirred again at room temperaturefor 15 minutes. The organic layer was separated and another 75 ml ofmethyl alcohol and 100 ml of distilled water were added to the separatedorganic layer. The organic layer was separated again and dried overmagnesium sulfate. After filtering, the solvent was then removed undervacuum. The resulting material was a colorless copoly(carbosilane andsiloxane) with a viscosity of 4400 cps and a refractive index of 1.465.

EXAMPLE 4

[0044] In a 500 ml three-necked round bottom flask, 41.0 grams ofoctaphenylcyclotetrasiloxane, 99.0 grams ofoctamethylcyclotetrasiloxane, 6.1 grams ofvinyldimethylsiloxy-terminated oligo(carbosilane and siloxane) (B) and0.14 grams of N-catalyst were mixed. The mixture was stirred and heatedto 1000 to 120° C. for 2 to 4 hours until theoctaphenylcyclotetrasiloxane had completely dissolved and the mixtureturned into a viscous brown solution. The mixture was then cooled toroom temperature and 150 ml of methylene chloride was added and stirredinto the mixture. Next, 75 ml of methyl alcohol and 100 ml of distilledwater were added and the mixture was stirred again at room temperaturefor 15 minutes. The organic layer was separated and another 75 ml ofmethyl alcohol and 100 ml of distilled water were added to the separatedorganic layer. The organic layer was separated again and dried overmagnesium sulfate. After filtering, the solvent was then removed undervacuum. The resulting material was a colorless copoly(carbosilane andsiloxane) with a viscosity of 4200 cps and a refractive index of 1.462.

EXAMPLE 5

[0045] In a 500 ml three-necked round bottom flask, 44.6 grams ofoctaphenylcyclotetrasiloxane, 93.5 grams ofoctamethylcyclotetrasiloxane, 3.1 grams ofvinyldimethylsiloxy-terminated oligo(carbosilane and siloxane) (A) and0.14 grams of N-catalyst were mixed. The mixture was stirred and heatedto 100° to 120° C. for 2 to 4 hours until theoctaphenylcyclotetrasiloxane had completely dissolved and the mixtureturned into a viscous brown solution. The mixture was then cooled toroom temperature and 150 ml of methylene chloride was added and stirredinto the mixture. Next, 75 ml of methyl alcohol and 100 ml of distilledwater were added and the mixture was stirred again at room temperaturefor 15 minutes. The organic layer was separated and another 75 ml ofmethyl alcohol and 100 ml of distilled water were added to the separatedorganic layer. The organic layer was separated again and dried overmagnesium sulfate. After filtering, the solvent was then removed undervacuum. The resulting material was a colorless copoly(carbosilane andsiloxane) with a viscosity of 4600 cps and a refractive index of 1.466.

EXAMPLE 6

[0046] In a 500 ml three-necked round bottom flask, 40.0 grams ofoctaphenylcyclotetrasiloxane, 93.5 grams ofoctamethylcyclotetrasiloxane, 3.1 grams ofvinyldimethylsiloxy-terminated oligo(carbosilane and siloxane) (A) and0.14 grams of N-catalyst were mixed. The mixture was stirred and heatedto 100° to 120° C. for 2 to 4 hours until theoctaphenylcyclotetrasiloxane had completely dissolved and the mixtureturned into a viscous brown solution. The mixture was then cooled toroom temperature and 150 ml of methylene chloride was added and stirredinto the mixture. Next, 75 ml of methyl alcohol and 100 ml of distilledwater were added and the mixture was stirred again at room temperaturefor 15 minutes. The organic layer was separated and another 75 ml ofmethyl alcohol and 100 ml of distilled water were added to the separatedorganic layer. The organic layer was separated again and dried overmagnesium sulfate. After filtering, the solvent was then removed undervacuum. The resulting material was a colorless copoly(carbosilane andsiloxane) with a viscosity of 4150 cps and a refractive index of 1.462.

EXAMPLE 7

[0047] In a 500 ml three-necked round bottom flask, 41.0 grams ofoctaphenylcyclotetrasiloxane, 99.0 grams ofoctamethylcyclotetrasiloxane, 3.6 grams ofvinyldimethylsiloxy-terminated oligo(carbosilane and siloxane) (A) and0.17 grams of N-catalyst were mixed. The mixture was stirred and heatedto 100° to 120° C. for 2 to 4 hours until theoctaphenylcyclotetrasiloxane had completely dissolved and the mixtureturned into a viscous brown solution. The mixture was then cooled toroom temperature and 150 ml of methylene chloride was added and stirredinto the mixture. Next, 75 ml of methyl alcohol and 100 ml of distilledwater were added and the mixture was stirred again at room temperaturefor 15 minutes. The organic layer was separated and another 75 ml ofmethyl alcohol and 100 ml of distilled water were added to the separatedorganic layer. The organic layer was separated again and dried overmagnesium sulfate. After filtering, the solvent was then removed undervacuum. The resulting material was a colorless copoly(carbosilane andsiloxane) with a viscosity of 8650 cps and a refractive index of 1.461.

[0048] TABLE 1 summarizes the compositions and properties of thecopolymers of Examples 3 through 7. TABLE 1 Example #: 3 4 5 6 7Composition (g) D₄Ph 44.6 41.0 44.6 40.0 41.0 D₄ 93.5 99.0 93.5 93.599.0 OCS 5.1(B) 6.1(B) 3.1(A) 3.1(A) 3.6(A) N-catalyst 0.14 0.14 0.140.14 0.17 Properties Viscosity 4400 4200 4600 4150 8650 (cps) Refractive1.465 1.462 1.466 1.462 1.46 Index

EXAMPLE 8

[0049] The remaining examples illustrate the preparation of variousembodiments of the elastomer of the present invention from the exemplarycopolymers prepared in Examples 3 through 7.

[0050] In a 500 ml glass flask, 80.0 grams of the copolymer of Example 3was mixed with 24.0 grams of hexamethyldisilazane-treated silica. Themixture was mechanically stirred and heated to 120° C. for 2 to 5 hours.Then, the mixture was cooled to room temperature and 4.0 grams ofhydrodimethyl-terminated silicone crosslinking agent, 1.0 grams oftris(vinyldimethylsiloxysilane), 104.0 milligrams oftetravinyltetramethylcyclotetrasiloxane, and 26.0 milligrams of platinumdivinyl complex (2-3% platinum concentration in xylene) were added andmixed until the mixture turned clear. The mixture was degassed for about20 to 50 minutes to remove all air bubbles in the mixture. The mixturewas then transferred into a sheet casting fixture and cast at 150° C.for 1.5 hours. After cooling to room temperature, the sheet was removedand cut into the desired shape. The final product had an elongation of195% and a tensile strength of 260 psi.

EXAMPLE 9

[0051] In a 500 ml glass flask, 80.0 grams of the copolymer of Example 4was mixed with 16.0 grams of hexamethyldisilazane-treated silica. Themixture was stirred and heated to 120° C. for 2 to 5 hours. Then, themixture was cooled to room temperature and 2.0 gram ofhydrodimethyl-terminated silicone crosslinking agent, 104.0 milligramsof tetravinyltetramethylcyclotetrasiloxane, and 13.0 milligrams ofplatinum divinyl complex (2-3% platinum concentration in xylene) wereadded and mixed until the mixture turned clear. The mixture was degassedfor about 20 to 50 minutes to remove all air bubbles in the mixture. Themixture was then transferred into a sheet casting fixture and cast at150° C. for 1.5 hours. After cooling to room temperature, the sheet wasremoved and cut into the desired shape. The final product had anelongation of 150% and a tensile strength of 210 psi.

EXAMPLE 10

[0052] In a 500 ml glass flask, 80.0 grams of the copolymer of Example 5was mixed with 22.5 grams of hexamethyldisilazane-treated silica. Themixture was stirred and heated to 120° C. for 2 to 5 hours. Then, themixture was cooled to room temperature and 4.0 grams ofhydrodimethyl-terminated silicone crosslinking agent, 1.0 grams oftris(vinyldimethylsiloxysilane), 104.0 milligrams oftetravinyltetramethylcyclotetrasiloxane, and 26.0 milligrams of platinumdivinyl complex (2-3% platinum concentration in xylene) were added andmixed until the mixture turned clear. The mixture was degassed for about20 to 50 minutes to remove all air bubbles in the mixture. The mixturewas then transferred into a sheet casting fixture and cast at 150° C.for 1.5 hours. After cooling to room temperature, the sheet was removedand cut into the desired shape. The final product had an elongation of200% and a tensile strength of 210 psi.

EXAMPLE 11

[0053] In a 500 ml glass flask, 80.0 grams of the copolymer of Example 6was mixed with 24.0 grams of hexamethyldisilazane-treated silica. Themixture was stirred and heated to 120° C. for 2 to 5 hours. Then, themixture was cooled to room temperature and 4.0 grams ofhydrodimethyl-terminated silicone crosslinking agent, 104.0 milligramsof tetravinyltetramethylcyclotetrasiloxane, and 26.0 milligrams ofplatinum divinyl complex (2-3% platinum concentration in xylene) wereadded and mixed until the mixture turned clear. The mixture was degassedfor about 20 to 50 minutes to remove all air bubbles in the mixture. Themixture was then transferred into a sheet casting fixture and cast at150° C. for 1.5 hours. After cooling to room temperature, the sheet wasremoved and cut into the desired shape. The final product had anelongation of 200% and a tensile strength of 230 psi.

EXAMPLE 12

[0054] In a 500 ml glass flask, 80.0 grams of the copolymer of Example 7was mixed with 8.5 grams of hexamethyldisilazane-treated silica. Themixture was stirred and heated to 120° C. for 2 to S hours. Then, themixture was cooled to room temperature and 2.4 grams ofhydrodimethyl-terminated silicone crosslinking agent, 104.0 milligramsof tetravinyltetramethylcyclotetrasiloxane, and 26.0 milligrams ofplatinum divinyl complex (2-3% platinum concentration in xylene) wereadded and mixed until the mixture turned clear. The mixture was degassedfor about 20 to 50 minutes to remove all air bubbles in the mixture. Themixture was then transferred into a sheet casting fixture and cast at150° C for 1.5 hours. After cooling to room temperature, the sheet wasremoved and cut into the desired shape. The final product had anelongation of 180% and a tensile strength of 180 psi. TABLE 2 Table 2summarizes the elastomer compositions and properties of Examples 8through 12. Example #: 8 9 10 11 12 Composition (g) CPCS 80.0 80.0 80.080.0 80.0 Silica 24.0 16.0 22.5 22.5 8.5 Crosslinker 4.0 2.0 4.0 2.4 2.4TVDMS 1.0 1.0 TVTMCTS 0.104 0.104 0.104 0.104 0.104 Platinum Catalyst0.026 0.026 0.026 0.026 0.026 Properties Elongation (%) 195 150 200 200180 Tensile Strength (psi) 260 210 210 230 280

[0055] While several specific embodiments of the invention have beenillustrated and described, it will be apparent that variousmodifications can be made without departing from the spirit and scope ofthe invention. Accordingly, it is not intended that the invention belimited, except as by the appended claims.

What is claimed is:
 1. An ophthalmic lens formed from acopoly(carbosilane and siloxane) elastomer comprising: a copolymerhaving carbosilane repeat units and siloxane repeat units.
 2. Theophthalmic lens of claim 1, wherein the siloxane repeat units are eachindependently selected from the group consisting of dimethylsiloxane anddiphenylsiloxane.
 3. The ophthalmic lens of claim 1, wherein thecarbosilane repeat units each have a carbon chain with 2 to 12 carbonatoms.
 4. The ophthalmic lens of claim 1, wherein the copolymer furthercomprises terminal alkynyl groups.
 5. The ophthalmic lens of claim 4,wherein the terminal alkenyl group is selected from the group consistingof vinyl, allyl, vinylphenyl, allylphenyl, vinylbenzyl and allylbenzyl.6. The ophthalmic lens of claim 1, wherein the copolymer has thestructure:

wherein A is an alkynyl; R₁, R₂, R₃, and R₄ are each a hydrocarbongroup; Ph is a phenyl; n is an integer from 10 to 500; m is an integerfrom 5 to 100; o is an integer from 2 to 12; and p is an integer from 2to
 50. 7. The ophthalmic lens of claim 1, wherein the elastomer furthercomprises a platinum catalyst.
 8. The ophthalmic lens of claim 1,wherein the elastomer further comprises a crosslinking agent.
 9. Theophthalmic lens of claim 8, wherein the crosslinking agent is ahydrodimethyl-terminated silicone.
 10. The ophthalmic lens of claim 1,wherein the elastomer further comprises a filler that ishexamethyldisilozane-treated silica and silicone resin material.
 11. Theophthalmic lens of claim 1, wherein the elastomer further comprises a UVabsorbing compound selected from the group consisting of allyl ormethallyl functionalized benzotriazoles or benzophenones.
 12. Theophthalmic lens of claim 1, wherein the elastomer has a refractive indexof at least about 1.43.
 13. The ophthalmic lens of claim 1, wherein theophthalmic lens is an intraocular lens.
 14. An ophthalmic lens formedfrom a copoly(carbosilane and siloxane) elastomer comprising: acopolymer having carbosilane repeat units and siloxane repeat units, thecarbosilane repeat units each having a carbon chain with 2 to 12 carbonatoms and the siloxane repeat units each being independently selectedfrom the group consisting of dimethylsiloxane and diphenylsiloxane; aplatinum catalyst; a crosslinking agent that is ahydrodimethyl-terminated silicone; a filler that ishexamethyldisilozane-treated silica and silicone resin material; and aUV absorbing compound selected from the group consisting of allyl ormethallyl functionalized benzotriazoles or benzophenones.
 15. Theophthalmic lens of claim 14, wherein the copolymer has the structure:

wherein A is an alkynyl; R₁, R₂, R₃, and R₄ are each a hydrocarbongroup; Ph is a phenyl; n is an integer from 10 to 500; m is an integerfrom 5 to 100; o is an integer from 2 to 12; and p is an integer from 2to
 50. 16. The ophthalmic lens of claim 14, wherein the elastomer has arefractive index of at least about 1.43.
 17. The ophthalmic lens ofclaim 14, wherein the ophthalmic lens is an intraocular lens.
 18. Acopoly(carbosilane and siloxane) elastomer having a high refractiveindex and optical clarity comprising: a copolymer having carbosilanerepeat units and siloxane repeat units, the carbosilane repeat unitseach having a carbon chain with 2 to 12 carbon atoms and the siloxanerepeat units each being independently selected from the group consistingof dimethylsiloxane and diphenylsiloxane.
 19. The ophthalmic lens ofclaim 1, wherein the copolymer has the structure:

wherein A is an alkynyl; R₁, R₂, R₃, and R₄ are each a hydrocarbongroup; Ph is a phenyl; n is an integer from 10 to 500; m is an integerfrom 5 to 100; o is an integer from 2 to 12; and p is an integer from 2to
 50. 20. The elastomer of claim 18 further comprising a platinumcatalyst.
 21. The elastomer of claim 18 further comprising acrosslinking agent.
 22. The elastomer of claim 21, wherein thecrosslinking agent is a hydrodimethyl-terminated silicone.
 23. Theelastomer of claim 18 further comprising a filler that ishexamethyldisilazane-treated silica and silicone resin material.
 24. Theelastomer lens of claim 18 further comprising a UV absorbing compoundselected from the group consisting of allyl or methallyl functionalizedbenzotriazoles or benzophenones.
 25. The elastomer of claim 18, whereinthe elastomer has a refractive index of at least about 1.43.